'smirandarights. they said he could still pose a threat either because there are more bombs planted out there or he's connected to a larger terrorist cell. either way it has some lawmakers concerned. as investigators continue to interrogate their suspect some lawmakers argue he should be treated as an enemy combatant and denied an attorney for the time being. >> we should be allowed her intelligence-gathering purposes. >> investigators say they're still uncertain whether zocor and his brother tamerlan who died in a shoot-out on friday with police have any ties to fore te union issued a statement saying we must not waver from our tried and true justice system even in the most difficult of times. denial of rights is un-american and will only make it harder to obtain fair convictions. some liberal lawmakers agree and said they would be comfortable with tsarnaev being designated as an enemy combatant. >> i don't believe. it would beunconstitutional to >> it carries its own risk especially if that suspect is an american citizen. it could be challenged in court and that

yet to be charged in connection with the attack or been notified ofhismirandarights,however, this morning officials tell nbc news he's awake and using pen and paper to answer questions from investigators. all of this as the fbi says it has obtained surveillance footage showing tsarnaev putting down his backpack near the finish line just minutes before the explosion. massachusetts governor deval patrick says he's been briefed on the footage. >> the suspect took the backpack off, put it down, did not react when the first explosion went off and then moved away from the backpack in time for the second explosion, so pretty clear about his involvement and pretty chilling, frankly. >> all right, so while we wait on that video, i want you to look at these new infrared images released showing the final intense moments of the manhunt. stun grenades just exploded as police moved in to capture the 19-year-old, and it capped a nearly four-day search for dzhokhar and his older brother, tamerlan, and while the nation was reeling, we are getting word this morning that the brothers actually

that they don't have to read himhismirandarightsright away. as time passes, does the justification for that exception grow weaker? are they on ls strong ground? >> it sure does, because as you know, miranda rights are a bedrock constitutional principle. we all have the right to remain silent, t get an attorney and be advised of those rights. the public safety exemption is a very narrow exemption. there has to be an imminent threat to the public. it certainly seems less imminent. >> don't officials who say the terror is over, don't they kind of undercut that argument, and does it really matter in the end? >> this is certainly an argument that's going to be handed to this defendant's defense attorney when that time comes. there have been contradictory statements made that there is no public threat, there is no ticking bomb, thank goodness, apparently, based on what we know so far. so we're giving them an argument to use later. >> the issue is, the questioning that's permitted without miranda is very narrow in scope, correct? >> yes. it's about what the public threat is. it's not all